Electric knife



FIG. 1 is a perspective view of an electric knife showing our new design;

FIG. 2 is a right side view thereof, the left side being a mirror image;

FIG. 3 is a top plan view thereof;

FIG. 4 is an inverted plan view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a rear view thereof.

The broken lines directed to the environmental structures are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an electric knife, as shown and described. 